Electrical energy has been used for providing energy to automobiles. Among the advantages of electrical propulsion are its cleanliness and lack of emissions during driving, high efficiency, quietness, and reliability. During the early years of automotive development electrical propulsion was a formidable competitor to the internal combustion engine.
The internal combustion engine had a decided advantage over electric motors because of the greater onboard energy storage afforded by liquid fuel, especially petroleum distillates and gasoline. Early electric automobiles had only a short range, typically less than 40 miles, followed by a lengthy charging cycle. By comparison, fossil fuel powered vehicles can travel hundreds of miles and need only a quick refueling in order to go another several hundred miles.
The significant drawback of electrically propelled automobiles has been the low energy density of the batteries used as a power source. Early batteries were usually lead acid type, which were very heavy and added to the weight of the vehicle. Over the years, improvements have been made in battery technology to reduce the weight penalty, but progress has not been sufficient to radically change the relative range of electrically powered automobiles versus their gasoline powered counterparts.
Recently, lithium ion batteries have been introduced which reduce the weight and increase the driving range of electric automobiles, but they are very expensive so that their most promising application is in hybrid automobiles where a smaller battery is sufficient. The small battery means that the primary energy source is still a gasoline powered engine.
Capacitors store electric energy. A capacitor usually includes a pair of electrodes that are configured on each side of a dielectric material to increase energy storage. The amount of energy stored by the capacitor is directly proportional to the dielectric constant. Thus the higher the dielectric constant, the greater the energy storage. Accordingly, efforts are being undertaken to develop dielectric materials with higher dielectric constants so that capacitors and related devices can be used for energy storage for powering devices and machinery including as automobiles.